JP2020112714A - Virtual image display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of ghost, to enable, for example, display of high-quality and wide-angle video, to provide high-quality video, and further to downsize an optical system and further downsize the entire device. To provide a virtual image display device capable of achieving. A video element that displays an image, a projection optical system that projects an image from the video element, a first diaphragm that forms a first opening in the projection optical system, and a second aperture in the projection optical system. A two-stage structure diaphragm having a second diaphragm that forms a portion, and the inclination of the chief ray of the image light emitted from the peripheral portion of the image surface of the image element with respect to the image plane is The first direction and the second direction perpendicular to the first direction are different from each other, and the first diaphragm and the second diaphragm in the two-stage structure diaphragm are the inclinations of the chief rays in the first direction and the second direction. They are provided at different positions depending on the difference. [Selection diagram] Figure 1

Description

The present invention relates to a virtual image display device represented by a head mounted display.

As a virtual image display device such as a head-mounted display, for example, as shown in Patent Document 1, the optical system is a non-telecentric optical system including at least one asymmetric surface, a diaphragm is provided, and the size of the optical system is reduced while achieving high size. It is known to provide high quality images. In the following, the head mounted display is also referred to as HMD.

JP, 2017-116773, A

However, in the configuration illustrated in Patent Document 1, for example, an attempt is made to further widen the angle of view while suppressing an increase in the optical system, or to further reduce the size of the optical system while maintaining the optical accuracy. Then, with the configuration in which the diaphragm is provided only at one place, it may not be possible to effectively suppress ghosts inside and outside the screen.

A virtual image display device according to an aspect of the present invention includes a video element that displays an image, a projection optical system that projects an image from the video element, a first aperture that forms a first opening in the projection optical system, and a projection. A two-stage diaphragm having a second diaphragm that forms a second aperture in the optical system, and the inclination of the chief ray of the image light emitted from the peripheral portion of the image plane of the image element with respect to the image plane is The first direction of the in-plane directions of the image plane is different from the second direction perpendicular to the first direction, and the first diaphragm and the second diaphragm in the two-stage structure diaphragm are the first direction and the second direction. They are provided at different positions according to the difference in the inclination of the chief ray at and.

It is a perspective view explaining an appearance of an example of a virtual image display device concerning a 1st embodiment. FIG. 3 is a perspective view showing an optical system and an optical path of image light in the virtual image display device. FIG. 3 is a plan view showing an optical system and an optical path of image light in the virtual image display device. FIG. 3 is a side view showing an optical system and an optical path of image light in the virtual image display device. It is a conceptual diagram for demonstrating the inclination of the principal ray in image light. It is a side sectional view for explaining one example of composition of a projection optical system. It is a plane sectional view for explaining an example of 1 composition of a projection optical system. It is a perspective view for explaining an example of 1 composition of the 1st diaphragm. It is a top view for explaining an example of 1 composition of the 1st diaphragm. It is a front view for explaining an example of 1 composition of the 1st diaphragm. It is a front view for explaining an example of 1 composition of the 2nd diaphragm. It is an optical path figure explaining an example of the virtual image display concerning a 2nd embodiment. It is a plane sectional view showing an optical system and an optical path of image light in an example of a virtual image display concerning a 3rd embodiment. FIG. 3 is a side sectional view showing an optical system and an optical path of image light in the virtual image display device. It is a conceptual diagram for demonstrating the inclination of the principal ray in image light. It is a figure for demonstrating one modification regarding the attachment structure of the 1st diaphragm. It is a figure for demonstrating another modification about the attachment structure of a 1st diaphragm.

[First Embodiment]
Hereinafter, the virtual image display device according to the first embodiment of the present invention will be described in detail with reference to FIG. 1 and the like.

As shown in FIG. 1 and the like, the virtual image display device 100 according to the present embodiment is a head mounted display (HMD) having an appearance like glasses, and for an observer or a user wearing the virtual image display device 100. The image light (image light) by the virtual image can be visually recognized, and the observer can visually see or observe the outside world image. The virtual image display device 100 includes a first display device 100A, a second display device 100B, and a frame unit 102.

The first display device 100A and the second display device 100B are portions that form a virtual image for the left eye and a virtual image for the right eye, respectively, and first and second optical members 101a and 101b that cover the viewer's eye in a see-through manner. , And first and second image forming main body portions 105a and 105b, respectively. The first and second image forming main body portions 105a and 105b will be described later, but each is composed of an optical system for image formation such as a display device (video element) and a projection lens, a member that accommodates these optical systems, and the like. Has been done. Note that the display device (video element), the projection lens, and the like are supported and housed by being covered with a cover-shaped exterior member (case member) 105d. The first and second optical members 101a and 101b guide the image light formed by the first and second image forming main bodies 105a and 105b, and at the same time, allow the external light and the image light to overlap and be visually recognized. And constitutes a light guide device including the light guide member. Hereinafter, the first optical member 101a or the second optical member 101b is also referred to as the light guide device 20. It should be noted that the first display device 100A and the second display device 100B independently function as a virtual image display device.

The frame portion 102 is an elongated member that is bent in a U shape in a plan view, and has a thick structure that is provided by being connected to both the first optical member 101a and the second optical member 101b, that is, the pair of light guide devices 20. It has a central portion 102a and a support body 102b extending from the central portion 102a along the first and second optical members 101a and 101b, and further forming a U-shaped bent portion.

A temple 104, which is a hanging portion extending rearward from both left and right ends of the frame portion 102, is provided, and the temple 104 can be used as a member that comes into contact with and supports an ear or temple of an observer.

An example of the structure for guiding the image light GL by the virtual image display device 100 will be conceptually described below with reference to FIG. 2 and the like. 2 to 4 are views showing a part of the first display device 100A, and in particular, an optical system part is extracted. As described above, the devices for guiding the image light GL are the first display device 100A and the second display device 100B (see FIG. 1 and the like), but the first display device 100A and the second display device 100A and the second display device 100B. Since the display device 100B has a bilaterally symmetrical and equivalent structure, only the first display device 100A will be described, and description of the second display device 100B will be omitted.

As shown in FIGS. 2 to 4, the first display device 100A includes an image display device 80 that forms the image light GL and a projection lens LS for image formation that is housed in the lens barrel BR shown in FIG. 6 and the like. The projection optical system 30 and the light guide device 20 that guides the image light GL that has passed through the image display device 80 and the projection lens LS are provided. The light guide device 20 includes a light guide member 10 for light guiding and see-through, and a light transmitting member 50 for see-through.

The image display device 80 can be, for example, a video element (video display element) including a self-luminous element such as an organic EL. Further, the image display device 80 includes, for example, a video display element that is a transmissive spatial light modulator, a lighting device that is a backlight that emits illumination light to the video display element, and a drive control unit that controls the operation. May be Here, as illustrated, the image display device 80 has a rectangular shape, forms a rectangular image plane IP, and emits the image light GL from each position of the image plane IP. Here, it is assumed that the normal direction of the image plane IP is the z direction, and the z direction coincides with the optical axis direction in which the optical axis AX of the projection lens LS forming the projection optical system 30 extends. Further, of the in-plane directions of the image plane IP perpendicular to the z direction, one direction of the rectangular image plane IP or the image display device 80 is the x direction, and the direction perpendicular to the x direction is the y direction. Here, the longitudinal direction of the rectangle is the x direction.

Further, in the above description, as shown in, for example, FIG. 3 and FIG. 4, of the image light GL emitted from the image plane IP of the image display device 80, the main component light GLp emitted from the peripheral portion PP of the image plane IP is mainly included. The light ray is inclined inward as compared with the principal ray of the component light GLc emitted from the center CC of the image plane IP. In other words, the center side component light GLc is parallel or substantially parallel to the optical axis AX, while the peripheral side component light GLp is inclined toward the center side so as to approach the optical axis AX. Furthermore, the degree of inclination of the chief ray differs between the inclination in the x direction and the inclination in the y direction. More specifically, as shown by comparison in FIG. 5, in the principal ray PRp of the spectrum GLp, the inclination angle α indicating the inclination with respect to the optical axis AX in the y direction is the inclination with respect to the optical axis AX in the x direction. Is larger than the inclination angle β. In other words, the chief ray PRp is inclined so that the vertical emission angle indicated by the inclination angle α is larger than the inclination angle β, that is, the horizontal emission angle, and is more inward in the vertical direction (y direction). The chief ray PRc of the component light GLc is parallel to the optical axis AX. Hereinafter, as an expression relating to the inclination of the principal ray PRp, the x direction is the first direction D1 and the y direction is the second direction D2. That is, with respect to the principal ray PRp of the component light GLp which is the image light GL emitted from the peripheral portion PP of the image plane IP, the inclination with respect to the image plane IP is the first direction D1 of the in-plane directions of the image plane IP and the first direction D1. It differs from the second direction D2 which is perpendicular to the first direction D1.

Returning to FIG. 2 to FIG. 4, the projection optical system 30 has a plurality of optical elements (in the illustrated example, aligned as the constituent elements, for example, along the direction in which the incident-side optical axis AX extends (optical axis direction; z direction). The projection lens LS includes four lenses LS1 to LS4), and the projection lens LS is housed and supported by an optical component holding member (a lens barrel BR shown in FIG. 6 and the like). Further, in the present embodiment, in the projection optical system 30, as shown in FIGS. 3 and 4, the first opening portion is located relatively downstream of the optical path on the optical path along the incident side optical axis AX. There is provided a two-stage structure diaphragm DS having a first diaphragm ST1 that forms a second aperture ST2 that forms a second aperture that is located relatively upstream of the optical path. First, as shown in FIG. 3, the first aperture stop ST1 is provided at the optimum aperture position where the diameter of the light flux of the image light GL is minimized when the entire image light GL is viewed in the first direction D1. There is. On the other hand, as shown in FIG. 4, the second aperture stop ST2 is provided at the optimum aperture position where the diameter of the light flux of the image light GL is minimized when the entire image light GL is viewed in the second direction D2. There is. As a result, the first diaphragm ST1 and the second diaphragm ST2 are provided at different positions depending on the difference in inclination of the principal ray PRp in the first direction D1 and the second direction D2. More specifically, in the case of the drawing, with respect to the inclination of the principal ray PRp, the inclination in the second direction D2 is larger than the inclination in the first direction D1, that is, the inclination angle in FIG. As α becomes larger than the tilt angle β, the second diaphragm ST2 of the two-stage structure diaphragm DS is arranged closer to the image display device 80 than the first diaphragm ST1 on the optical path. .. In other words, of the two-stage structure diaphragm DS, the first diaphragm ST1 functions as a diaphragm for the image light GL corresponding to the inclination in the first direction D1, and the second diaphragm ST2 is the inclination in the second direction D2. Corresponding to, it functions as a diaphragm for the image light GL. That is, in this case, the first diaphragm ST1 is a diaphragm in the horizontal direction, and the second diaphragm ST2 is a diaphragm in the vertical direction. Since the two-stage structure diaphragm DS has the first and second diaphragms ST1 and ST2 having the above-described arrangement relationship, the light is appropriately adjusted and the occurrence of ghost is suppressed. Further, among the lenses LS1 to LS4, there is one that is composed of, for example, an aspherical lens including both an axisymmetric aspherical surface (axisymmetric aspherical surface) and an axisymmetric aspherical surface (axisymmetric aspherical surface). include. That is, the projection lens LS constitutes an asymmetrical optical system. Thereby, an intermediate image corresponding to a display image can be formed inside the light guide member 10 in cooperation with a part of the light guide member 10 that constitutes the light guide device 20. The projection lens LS projects the image light GL formed by the image display device 80 toward the light guide device 20 and makes it enter. Although not described in detail, the lens barrel BR is housed and supported by the exterior member 105d (see FIG. 1).

In the HMD, a certain number of lenses is required to improve the resolution performance and distortion of each optical system represented by the projection optical system 30 in the figure. However, increasing the number of lenses leads to an increase in the size of the optical system. Further, in order to reduce the size, it is necessary to reduce the distance between lenses as much as possible. In the present embodiment, in order to realize a more compact optical system, the lens is arranged between the vertical and horizontal diaphragm positions, that is, between the first diaphragm ST1 and the second diaphragm ST2.

As described above, the light guide device 20 is composed of the light guide member 10 for light guiding and see-through, and the light transmitting member 50 for see-through. Further, the light guide device 20 has the main body member covered and protected by the hard coat layer being a protective layer provided on the surface portion. The light transmitting member 50 is a member (auxiliary optical block) that assists the see-through function of the light guide member 10, that is, a light transmitting portion, and is integrally fixed to the light guide member 10 to form one light guide device 20. .. The light guide device 20 is accurately positioned and fixed to the projection lens LS by being screwed to an optical component holding member such as a lens barrel BR.

The light guide member 10 has first to fifth surfaces S11 to S15 as side surfaces having an optical function. Of these, the first surface S11 and the fourth surface S14 are adjacent to each other, and the third surface S13 and the fifth surface S15 are adjacent to each other. Further, the second surface S12 is arranged between the first surface S11 and the third surface S13. A half mirror layer is additionally provided on the surface of the second surface S12. The half mirror layer is a light-transmitting reflective film (semi-transmissive reflective film), and is formed by depositing a metal reflective film or a dielectric multilayer film, and the reflectance for image light is appropriately set. That is, the light guide member 10 has a transmissive reflection surface that covers the front of the eye when the observer wears it.

As described above, the light transmission member 50 is integrally fixed to the light guide member 10 to form one light guide device 20, and is a member (auxiliary optical block) that assists the see-through function of the light guide member 10. .. The light transmitting member 50, which is a light transmitting portion, has a first transmitting surface S51, a second transmitting surface S52, and a third transmitting surface S53 as side surfaces having an optical function. The second transmission surface S52 is arranged between the first transmission surface S51 and the third transmission surface S53. The first transmission surface S51 is on a surface that is an extension of the first surface S11 of the light guide member 10, and the second transmission surface S52 is a curved surface that is joined and integrated with the second surface S12. The three-transmission surface S53 is on a surface that is an extension of the third surface S13 of the light guide member 10. In other words, the first surface S11 and the first transmissive surface S51 are adjacent to each other, and similarly, the third surface S13 and the third transmissive surface S53 are adjacent to each other, both of which are aligned flush with each other. It forms a smooth surface.

Hereinafter, the optical path of the image light GL will be briefly described with reference to FIG. The light guide member 10 allows the image light GL to enter from the projection lens LS and guides the image light GL toward the eyes of the observer by reflection on the first to fifth surfaces S11 to S15. Specifically, the image light GL from the projection lens LS first enters the fourth surface S14 and is reflected by the fifth surface S15, and again enters the fourth surface S14 from the inside and is totally reflected. It is incident on the surface S13 and totally reflected, and is incident on the first surface S11 and totally reflected. The image light GL totally reflected by the first surface S11 is incident on the second surface S12 and partially reflected while being partially transmitted through the half mirror layer provided on the second surface S12. It re-enters and passes through. The image light GL that has passed through the first surface S11 is incident on the observer's eye or its equivalent position as a substantially parallel light flux. That is, the observer observes the image with the image light GL as the virtual image.

Further, the light guide device 20 allows the observer to visually recognize the image light through the light guide member 10 as described above, and the cooperation of the light guide member 10 and the light transmission member 50 allows the observer to form an external image with less distortion. It is supposed to be observed. At this time, since the third surface S13 and the first surface S11 are planes that are substantially parallel to each other (diopter is substantially 0), aberrations and the like hardly occur in the external light. Similarly, the third transmitting surface S53 and the first transmitting surface S51 are planes that are substantially parallel to each other. Furthermore, since the third transmitting surface S53 and the first surface S11 are planes that are substantially parallel to each other, aberrations and the like hardly occur. As described above, the observer observes the distortion-free external image through the light transmitting member 50.

As described above, in the present embodiment, in the inside of the light guide member 10, the image light from the image display device 80, as described above, includes the first surface S11 to the fifth surface including the total reflection at least twice. Light is guided by five reflections up to S15. This makes it possible to achieve both display of image light and see-through for visually recognizing external light, and to correct aberration of the image light GL.

The above-described configuration is the same in the second display device 100B (see FIG. 1). This makes it possible to form images corresponding to the left and right eyes, respectively.

Hereinafter, visual recognition of the virtual image by the virtual image display device 100 will be described. First, in the illustrated example, the eye box EB showing a range in which a virtual image by the image light GL can be visually recognized by an observer is shown by a rectangular surface. In general, the actual surface shape of the eye box EB varies depending on the design, but typically, it is often a circle or a square. On the other hand, in the present embodiment, the eye box EB is a horizontally long rectangle (h<w). As described above, the eye box EB is a range in which the components of the image lights GL that are substantially parallel light beams and are emitted from the first surface S11 overlap. That is, in order for the image to be visually recognized without being lost, it is necessary to place the eyes of the observer within the range of the surface formed by the eye box EB. In general, the human eye moves well in the horizontal direction arranged side by side and has a wide field of view. Therefore, a horizontally long image is often formed in the horizontal direction, which is also the case in the present embodiment, for example. Further, since there is an individual difference in the interpupillary distance, in the case of the left-right pair configuration as in the present embodiment, in order to eliminate the need for the interpupillary adjustment mechanism, it is necessary to set the eyebox EB to some extent in the horizontal direction in which the eyes are lined up. Tolerance is required. From such a situation, regarding the shape of the eye box EB, in the in-plane direction in the plane of the eye box EB, the horizontal direction along the alignment of the eyes of the observer at the time of observation is made larger than the vertical direction perpendicular to the horizontal direction. It is better to keep it. In the figure, the Z direction indicates the normal direction to the surface of the eye box EB, and the X direction indicates the horizontal direction along the eye alignment of the in-plane directions on the surface of the eye box EB. In the Y direction.

In the present embodiment, based on the above situation, the image light GL emitted from the peripheral portion PP of the image plane IP is horizontally oriented in the second direction D2 (y direction) corresponding to the vertical direction (Y direction). A two-stage structure diaphragm DS having a configuration tilted from a first direction D1 (x direction) corresponding to the direction (X direction) and further having a first diaphragm ST1 and a second diaphragm ST2 corresponding thereto is provided. This enables high-quality and wide-angle video display, while also achieving downsizing of the optical system and, in turn, downsizing of the entire device, while suppressing the occurrence of ghosts and providing high-quality video. Is maintained.

The above will be described in more detail. First, as described above, the eye box is typically designed to be a circle or a square in many cases, whereas the eye box EB of the present embodiment has a horizontal direction. It's getting bigger. Accordingly, the swallowing angle (eg, 13.5°) of the image light GL emitted from the image display device 80 in the horizontal direction is smaller than the swallowing angle of the image light GL in the vertical direction (eg, 7.5°). ) Is larger than. Therefore, when the principal ray angle of the image light GL is made equal in the horizontal and vertical directions, the luminous flux width at the exit position of the projection optical system 30 becomes larger in the horizontal direction. This is not desirable, especially in a laterally developed HMD optical system, because it leads to an increase in the lateral width of the product, which greatly affects the appearance of the product. For the above reason, in the present embodiment, the principal ray angle of the image light GL to be emitted can be suppressed in the lateral width of each optical system by inclining it further inward in the vertical cross-sectional direction, thereby increasing the angle of view and downsizing the product. The trade-off of can be improved.

Further, if the principal ray angle is different between the vertical section and the horizontal section, the position at which the ray bundle of the image light GL is most converged is also significantly different between the vertical section and the horizontal section. For example, when the exit angle is more inward from the image display device 80, the convergent position of the light flux is closer to the image display device 80. In the present embodiment, by taking this into consideration, the optimum arrangement position of the first aperture stop ST1 and the second aperture stop ST2 is determined, so that the ghost light can be particularly suppressed.

Hereinafter, one configuration example of the projection optical system 30 will be described more specifically with reference to FIG. 6 and the like. As shown in FIGS. 6 and 7, and as described above, the projection lens LS of the projection optical system 30 has four lenses LS1 to LS4 in order from the side far from the optical image display device 80, These are housed in one lens barrel BR integrally formed. The lens barrel BR is manufactured by, for example, resin molding. Further, here, a two-stage structure diaphragm DS including two diaphragms ST1 and ST2 is provided between the four lenses LS1 to LS4 of the projection optical system 30. In the illustrated example, of the two-stage structure diaphragm DS, the first diaphragm ST1 located on the downstream side of the optical path is provided between the first lens LS1 and the second lens LS2, and is located on the upstream side of the optical path. The two diaphragms ST2 are provided between the third lens LS3 and the fourth lens LS4. From a different point of view, a lens forming the projection optical system 30 is inserted between the first diaphragm ST1 and the second diaphragm ST2.

In the illustrated example, in the two-stage structure diaphragm DS, one first diaphragm ST1 is composed of a mounting member MM that is separate from the lens barrel BR, and the other second diaphragm ST2 is a part of the lens barrel BR. Is integrally molded as. In this case, the second diaphragm ST2 forms the most constricted part in the cylindrical lens barrel BR. Further, in the example here, the first aperture stop ST1 is made of a black tape as the mounting member MM. The structure of the first aperture stop ST1 will be described later with reference to FIG.

In this case, first, as shown in FIG. 6, the second diaphragm ST2 is provided at the optimum diaphragm position between the third lens LS3 and the fourth lens LS4 on the inner surface of the lens barrel BR. From a different point of view, the lens barrel BR forms a protrusion TP to be the second diaphragm ST2 between the positioning portion DT3 of the third lens LS3 and the positioning portion DT4 of the fourth lens LS4. Even when the lens barrel BR is manufactured by injection molding, the protruding portion TP is the reference position that projects the innermost portion.

Next, as shown in FIG. 7, the first aperture stop ST1 is provided at the optimum aperture position between the first lens LS1 and the second lens LS2 by attaching the attachment member MM to the first lens LS1. ..

Hereinafter, the first aperture stop ST1 formed by the mounting member MM will be described in more detail with reference to FIGS. 8 and 9. First, the mounting member MM to be the first diaphragm ST1 is a black sheet-shaped tape member, and the opening H1 that defines the shape of the light transmission region in the opening OP1 of the first diaphragm ST1 as well as the first lens LS1. Among them, four holes HL are provided so as to fit into four positioning bosses BS provided at four corners outside the effective lens diameter. That is, by fitting each hole HL into the corresponding boss BS, the mounting member MM is accurately positioned with respect to the first lens LS1, and the first aperture stop ST1 having the opening OP1 is formed. Further, in this case, since the tip end portion of the boss BS is the contact surface with the second lens LS2, that is, the contact surface with another lens or the lens barrel, the first lens LS1 It is used for positioning in the optical axis direction. Further, for example, as shown in the front view of FIG. 10, the four bosses BS and the holes HL are symmetrically provided at the four corners. That is, they are arranged in a target positional relationship around the optical axis AX shown in FIG. It should be noted that the bending of the sheet-shaped first aperture stop ST1 and the like are prevented from occurring due to the existence of the boss BS and the hole HL. Further, the sheet-shaped mounting member MM is preliminarily formed with a pressure sensitive adhesive, and is adhered to the first lens LS1 when it is mounted. In this case, the adhesive is attached between the mounting member MM and the first lens LS1 on the optical path downstream side of the mounting member MM. That is, the adhesive is arranged on the side of the attachment member MM opposite to the image display device 80. As a result, it is possible to avoid deterioration of the function of preventing reflection of unnecessary light from the image display device 80 side due to the adhesive. That is, as compared with the case where the adhesive is applied in the opposite direction to the above, light reflection is less likely to occur in the adhesive layer, and unexpected ghost generation is suppressed.

As a method other than the assembling structure using the boss BS and the hole HL as described above, for example, the outer shape of the light shielding sheet to be the first aperture stop ST1 is exactly fitted to the concave portion provided in the lens or the barrel (barrel). It is conceivable that the structure is such that they are stuck together so that However, in this case, since it is possible to assemble even if it is fitted in a state where it is slightly displaced at the time of assembly, it becomes difficult to control the assembly accuracy. There is no problem if the light-shielding sheet to be used is a sheet metal or resin parts with a strong rigidity, but when using a sheet member with a relatively weak rigidity, it is assembled with the internal flexure etc. still occurring. There is a possibility that it will end up. In the above, by forming the hole HL of the sheet-shaped member to be the first aperture stop ST1 into the boss BS which is a protrusion provided on the lens LS1 or the like, there is no occurrence of bending and there is no deviation during assembly. It is hard to occur.

With the configuration as described above, when assembling the projection optical system 30, first, the third lens LS3 is installed from the side opposite to the assembly side of the image display device 80 with the positioning portion DT3 provided on the inner surface of the lens barrel BR as a reference. Assembly, and further, the second lens LS2 is assembled with reference to the positioning portion DT2. After that, the first lens LS1 to which the attachment member MM is attached in advance is attached to the inner surface of the lens barrel BR from the side opposite to the attachment side of the image display device 80 with the positioning portion DT1 as a reference, and finally, the image display device 80. The fourth lens LS4 is assembled from the assembling side with reference to the positioning portion DT4. As described above, the projection optical system 30 as one unit is manufactured.

As described above, when the diaphragm is provided in the lens barrel BR, if the lens barrel BR is a resin molded component, a metal cutting component, or the like, the diaphragm can be formed in only one place due to the processing method. Therefore, in the above description, one stop is formed in the lens barrel BR, and the other stop is formed by disposing the mounting member MM which is a light shielding sheet (black tape) disposed between the lenses. A more specific example of the mounting member MM will be described. The mounting member MM is a light-shielding sheet formed of black tape or the like, that is, a black sheet member. In the example shown in FIG. 8 and FIG. 9, the mounting member MM has a configuration in which it is wrapped around at least a part of the lens LS1 and attached. As a result, it is possible to improve the adhesion to the lens LS1 and suppress the occurrence of light leakage and the like due to internal reflection near the lens LS1 and the influence thereof on the image light and the like.

In the projection optical system 30 as described above, in the first diaphragm ST1 and the second diaphragm ST2, the light flux of the image light GL is thinner in the second diaphragm ST2. For example, as shown in FIGS. 10 and 11, the second direction opening width W2, which is the opening width in the second direction D2 of the second opening OP2 that forms the opening H2 in the second diaphragm ST2, is the first diaphragm. In ST1, it is smaller than the first-direction opening width W1 that is the opening width in the first direction D1 of the first opening OP1 that forms the opening H1. For example, the first direction opening width W1 may be about 8.5 mm, while the second direction opening width W2 may be about 4.25 mm. Further, as shown in FIG. 11, regarding the shape of the opening H2, the opening width in the first direction D1 is larger than the opening width in the second direction D2 (that is, the opening width W2 in the second direction). ..

As described above, the virtual image display device 100 according to the present embodiment includes the image display device 80 that is a video element that displays an image, the projection optical system 30 that projects the video light GL from the image display device 80, and the projection optical system. A two-stage structure diaphragm DS having a first diaphragm ST1 forming a first opening OP1 in the system 30 and a second diaphragm ST2 forming a second opening OP2 in the projection optical system 30 is provided. Regarding the principal ray PRp of the image light GL emitted from the peripheral portion of the image plane IP of the device 80, the inclination with respect to the image plane IP is perpendicular to the first direction D1 and the first direction D1 of the in-plane directions of the image plane IP. The second stop D1 differs from the first stop ST1 and the second stop ST2 in the two-stage structure stop DS in accordance with the difference in inclination of the chief ray PRp between the first direction D1 and the second direction D2. They are provided at different positions.

In the virtual image display device 100, in the two-stage structure diaphragm DS, the first diaphragm ST1 and the second diaphragm ST2 are the first direction D1 of the in-plane directions of the image plane IP of the image display device 80 which is a video element. The image light GL can be appropriately adjusted by being provided at different positions depending on the difference in inclination of the principal ray PRp in the second direction D2. More specifically, in the present embodiment, the inclination of the principal ray PRp in the peripheral portion of the image display device 80 is larger in the second direction D2 than in the first direction D1. Correspondingly, in the two-stage structure diaphragm DS, the first diaphragm ST1 is a diaphragm in the first direction D1 and the second diaphragm ST2 is a diaphragm in the second direction D2. This suppresses the occurrence of ghosts, for example, enables high-quality and wide-angle image display, provides high-quality images, and further downsizing the optical system, and thus downsizing the entire device. It becomes possible to plan.

[Second Embodiment]
An example of the virtual image display device according to the second embodiment will be described below with reference to FIG.

The virtual image display device according to the present embodiment is a modified example of the virtual image display device illustrated in the first embodiment, and is the same as the case of the first embodiment except for the direction in which the image light GL is guided. A description of the entire virtual image display device will be omitted.

FIG. 12 is an optical path diagram for describing one configuration example of the virtual image display device 200 according to the present embodiment, and also shows a conceptual configuration and is a diagram corresponding to FIG. 3. In the example of FIG. 3, the image light GL is guided in the left-right direction along the horizontal direction along the eye alignment, whereas in the present embodiment, the image light GL is guided in the up-down direction along the horizontal direction. The image light GL is guided. Also in this case, the first diaphragm ST1 and the second diaphragm ST2 which are tilted with respect to the image light GL emitted from the image plane IP of the image display device 280 and constitute the two-stage structure diaphragm DS with respect to the projection optical system 230. By arranging at different positions on the optical path according to the inclination of the image light GL emitted from the image plane IP, it is possible to suppress the occurrence of ghosts and, for example, enable high-quality and wide-angle image display, It is possible to provide high-quality images and further downsize the optical system, and thus downsize the entire apparatus.

[Third Embodiment]
Hereinafter, an example of the virtual image display device according to the third embodiment will be described with reference to FIG. 13 and the like.

The virtual image display device according to the present embodiment is a modified example of the virtual image display device illustrated in the first embodiment, and the first embodiment except the structure of the optical system forming the first display device and the second display device. Since it is similar to the case of 1, the description of the entire virtual image display device will be omitted. Further, since the first display device and the second display device have symmetrical and equivalent structures, only the first display device will be described, and description of the second display device will be omitted. In the optical system of the first embodiment, the same reference numerals are given, and those that are not particularly described are the same as those of the first embodiment.

FIG. 13 is a plan sectional view for explaining one configuration example of the virtual image display device 300 according to the present embodiment, and shows the first display device 300A for the left eye of the virtual image display device 300. Further, FIG. 14 is a side sectional view of the first display device 300A. Further, FIG. 15 is a conceptual diagram for explaining the inclination of the principal ray in the image light, and is a diagram corresponding to FIG. 5.

As shown in FIGS. 13 to 15, in the present embodiment, in the two-stage structure diaphragm DS, the first diaphragm ST1 located relatively downstream of the optical path and the second diaphragm ST2 located relatively upstream of the optical path. Is different from that of the first embodiment. In short, as shown in FIG. 14, the first diaphragm ST1 arranged on the downstream side of the optical path, that is, at the position relatively far from the image display device 80 is a diaphragm in the vertical direction. On the other hand, as shown in FIG. 13, the second diaphragm ST2 arranged on the upstream side of the optical path, that is, on the upstream side of the optical path, that is, at a position relatively close to the image display device 80, is a diaphragm in the horizontal direction. In the virtual image display device 300 according to the present embodiment, as shown in FIG. 15, the inclination of the principal ray PRp is set so that the inclination in the second direction D2 is larger than the inclination in the first direction D1. This is because it corresponds to the configuration in which the inclination angle α is larger than the inclination angle β in FIG. In the present embodiment as well, the two-stage structure diaphragm DS has the first and second diaphragms ST1 and ST2 having the above-described arrangement relationship, so that the light is appropriately adjusted and the ghost is generated. It's suppressed.

As described above, also in the present embodiment, as in the case of the first embodiment, the first aperture stop ST1 forming the first opening in the projection optical system 30 and the second opening in the projection optical system 30 are formed. In the two-stage structure diaphragm DS having the second diaphragm ST2 to be formed, the second diaphragm ST2 is arranged closer to the image display device 80 than the first diaphragm ST1 on the optical path, and the first diaphragm ST1 and the second diaphragm ST2 The aperture stop ST2 is an aperture stop in a different direction. On the other hand, in the present embodiment, unlike the case of the first embodiment, with respect to the inclination of the principal ray PRp in the peripheral portion of the image display device 80, the inclination in the second direction D2 is smaller than the inclination in the first direction D1. Is also getting smaller. Correspondingly, in the two-stage structure diaphragm DS, the first diaphragm ST1 is a diaphragm in the second direction D2, and the second diaphragm ST2 is a diaphragm in the first direction D1. This suppresses the occurrence of ghosts, for example, enables high-quality and wide-angle image display, provides high-quality images, and further downsizing the optical system, and thus downsizing the entire device. It becomes possible to plan.

[Other]
Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments and can be implemented in various modes without departing from the scope of the invention.

First, of the above, for example, in the first embodiment, the second diaphragm ST2 is formed of the lens barrel BR, but in order to reduce the cost, for example, in the case of the lens barrel BR, the diaphragm is reduced. It is necessary to form an integrated part including the shape, and the part thickness of the narrowed part needs to be at least 0.7 mm or more. Therefore, for example, it is desirable to secure at least 1 mm or more between the lenses (edge interval) in which the second diaphragm ST2 is arranged.

In addition to the above, the first aperture stop ST1 may be, for example, a metal sheet metal, paper, a sheet material of plastic material, or a plastic molded member. Furthermore, a black-painted sheet metal may be used. As a method of fixing, in addition to adhesion to the lens, it may be arranged so as to be sandwiched between the lenses, or a plastic molding member or a snap fit structure (hook structure) between the metal plate and the lens. By applying a thin member such as a tape, reflection, scattering, etc. can be suppressed. In other words, by using a thin-walled component, it is possible to avoid a situation in which new ghost light is generated due to internal reflection due to the provision of the thick-walled side surface portion, and it is possible to effectively reduce the ghost light inside the lens barrel or the lens side portion. It can cut ghost light.

Regarding the structure for mounting the first aperture stop ST1, as shown in, for example, the perspective view F1, side view F2, and perspective view F3 of FIG. 16, the first aperture stop ST1 is sandwiched between the lens LS1 and the lens LS2. It may be arranged so as to be fixed and fixed. More specifically, first, as shown in the perspective view F1, the first aperture stop ST1 is moved by the attachment positioning portion AT provided by the projection portion and the hole corresponding to the projection portion in the lens LS1 and the first aperture stop ST1. It is in a state of being attached to the lens LS1. After that, as shown in the side view F2 and the perspective view F3, by assembling the lens LS2 and the first diaphragm ST1 with the first diaphragm ST1, as a result, the first diaphragm ST1 is placed between the lens LS1 and the lens LS2. It can be placed so that it is sandwiched between. In the above, instead of the lens LS1 and the like, a part of the member sandwiching the first diaphragm ST1 may be used as the contact surface of the lens barrel.

In the above case, the positioning is performed in a sandwiched manner without pasting with an adhesive, so that the bonding process can be omitted and the assembly cost can be suppressed as compared with the case where a sheet metal or a resin component is used.

Further, the shapes of the openings of the stops ST1 and ST2 may be left-right asymmetrical. For example, as illustrated in the front view G1 and the perspective view G2 of FIG. 17, it is conceivable that the opening H1 of the first diaphragm ST1 has a trapezoidal shape. In this case, in order to prevent a wrong assembly direction at the time of assembly, for example, as shown in FIG. 17, among the four positioning bosses BS and the corresponding four holes HL, the lower right position is positioned. It is conceivable to change only the hole diameter of No. 1 to one different from other hole diameters, or to make the hole arrangement asymmetric.

As illustrated in FIG. 17, the opening H1 of the first aperture stop ST1 has a vertically or horizontally asymmetrical shape, and at least one boss BS has a size or shape that is different from that of the other bosses BS with respect to the size of the positioning boss. Since the holes HL are different and the sizes of the corresponding holes HL are also different, it is possible to cope with the case where the telecentric angles of the components emitted from the image display device 80 are asymmetrical in the vertical and horizontal directions. That is, when the shape of the entire light flux on the light source side is asymmetrical, the shape of the opening H1 is also asymmetrical vertically or horizontally as described above, so that the ghost light can be cut more efficiently. It will be possible. Further, in this case, the shape of the boss and the hole corresponding thereto are changed so as not to be rotationally symmetric by changing at least one place from the other place so as not to make an incorrect assembly at the time of assembling.

Further, in the above description, the positioning boss BS and the corresponding hole HL are provided at the four corners with symmetry so that at least one pair of the positioning boss BS and the corresponding hole HL are arranged symmetrically with respect to the optical axis center. In the assembling, the assembly is performed without bending in the left-right and up-down directions. Ideally, as illustrated in FIG. However, the present invention is not limited to this, and by positioning at least one pair of positioning bosses symmetrically with respect to the center of the optical axis, it can be expected that the assembly accuracy is maintained to some extent.

Further, in the above description, as an example, the boss BS is provided on the first lens LS1 and the tip end portion thereof is brought into contact with the second lens LS2, thereby positioning the first lens LS1 in the optical axis direction. However, various aspects can be considered for the location where the boss BS is provided, and it is also possible to provide the boss BS on the lens of the projection optical system 30 other than the first lens LS1 or on the lens barrel BR.

Further, it is desirable that the positioning boss BS is provided at both ends in the longitudinal direction of the shape of the lens LS1 or the like in which it is provided. For example, when the lens shape is vertically long, at least one boss BS is provided on each of the upper and lower sides, so that the longer the distance between the bosses BS, the higher the assembling accuracy with respect to the rotation when the sheet is attached. Is.

Further, it may be configured by a plurality of lens barrels. For example, the three lenses LS1 to LS3 are fixed by the first lens barrel, the lens LS4 is fixed by the second lens barrel, and the first lens barrel and the second lens barrel are joined together to form a projection lens. It is also conceivable to configure the LS. In this case, two diaphragm positions can be secured in the lens barrel.

In addition to the above, as the image display device 80, in addition to HTPS as a transmissive liquid crystal display device, various other devices can be used. For example, a configuration using a reflective liquid crystal display device is also possible. Therefore, a digital micromirror device or the like can be used instead of the video display element such as a liquid crystal display device.

Further, the generation of ghost light or the like may be further suppressed by providing an AR coat on the lens surface of each lens as appropriate.

In addition to the so-called closed type (not see-through) type virtual image display device for visually recognizing only the image light, the technique of the present invention is adopted in a device that allows an observer to visually recognize or observe the external image, or It may be adapted to a so-called video see-through product including a display and an imaging device.

Further, the technique of the present invention can be applied to a binocular type handheld display and the like.

In addition, in the above, in place of the semi-transmissive reflective film that transmits a part of the image light and reflects the other part, an optical function surface such as a diffractive element such as a volume hologram is provided instead of this. Therefore, it may be possible to play an equivalent role.

As described above, the virtual image display device of one embodiment of the present invention includes a video element which displays an image, a projection optical system which projects an image from the video element, and a first opening portion in the projection optical system. A two-stage aperture having a first aperture and a second aperture forming a second opening in the projection optical system is provided, and the first aperture and the second aperture in the two-stage aperture are the image plane of the image element. Are provided at different positions according to the inclination of the principal ray of the image light emitted from the peripheral portion of the.

In the above virtual image display device, in the two-stage structure diaphragm, the first diaphragm and the second diaphragm are provided at different positions depending on the inclination of the principal ray of the image light emitted from the peripheral portion of the image plane of the image element. By doing so, the light can be adjusted appropriately. This suppresses the occurrence of ghosts, for example, enables high-quality and wide-angle image display, provides high-quality images, and further downsizing the optical system, and thus downsizing the entire device. It becomes possible to plan.

In a specific aspect of the invention, the inclination of the chief ray with respect to the image plane is different between the first direction of the in-plane directions of the image plane and the second direction perpendicular to the first direction. In this case, the light can be appropriately adjusted according to the difference in the inclination of the chief ray between the first direction and the second direction of the in-plane directions of the image plane of the image element.

According to another aspect of the present invention, a surface of the eye box showing a range in which a virtual image can be visually recognized by an observer is larger in a horizontal direction along an array of eyes at the time of observation than in a vertical direction perpendicular to the horizontal direction. Corresponds to the horizontal direction, and the second direction corresponds to the vertical direction. In this case, for example, in binocular vision, the interpupillary adjustment can be made unnecessary.

In still another aspect of the present invention, with respect to the inclination of the chief ray in the peripheral portion of the image element, the inclination in the second direction is larger than the inclination in the first direction, and in the two-stage structure diaphragm, the second diaphragm is It is arranged at a position closer to the image device than the first diaphragm on the optical path, the first diaphragm is a diaphragm in the first direction, and the second diaphragm is a diaphragm in the second direction. In this case, a diaphragm suitable for the difference in inclination can be provided.

In yet another aspect of the present invention, the second-direction opening width of the second opening is smaller than the first-direction opening width of the first opening. In this case, a diaphragm can be formed according to the light flux.

In still another aspect of the present invention, with respect to the inclination of the principal ray in the peripheral portion of the image element, the inclination in the second direction is smaller than the inclination in the first direction, and in the two-stage structure diaphragm, the second diaphragm is It is arranged closer to the image sensor than the first diaphragm on the optical path, the first diaphragm is a diaphragm in the second direction, and the second diaphragm is a diaphragm in the first direction. In this case, a diaphragm suitable for the difference in inclination can be provided.

In still another aspect of the present invention, the projection optical system forms an intermediate image to form an asymmetrical optical system. In this case, a high quality image can be formed while maintaining the optical path length suitable for the HMD.

In still another aspect of the present invention, the projection optical system has at least one lens disposed between the diaphragm position of the first diaphragm and the diaphragm position of the second diaphragm. In this case, the diaphragm can be arranged at the optimum diaphragm position.

In still another aspect of the present invention, in the two-stage structure diaphragm, one of the first diaphragm and the second diaphragm is integrally molded as a part of the lens barrel of the projection optical system, and the other is separate from the lens barrel. Is a mounting member. In this case, a two-stage structure diaphragm can be realized with a simple structure.

In yet another aspect of the present invention, the mounting member is a black sheet member. In this case, for example, a black sheet member made of black tape or the like can shield light.

In still another aspect of the present invention, the light guide member further includes a transmissive reflection surface that covers the front of the eye when the observer is wearing the light guide member. In this case, see-through can be realized.

As described above, a virtual image display device according to another aspect of the present invention forms a video element that displays an image, a projection optical system that projects an image from the video element, and a first opening in the projection optical system. And a second stop having a second stop that forms a second opening in the projection optical system. In the two-step structure stop, the second stop is more than the first stop on the optical path. The first diaphragm and the second diaphragm are arranged at positions close to the image element and are diaphragms in different directions.

In the above virtual image display device, in the two-stage structure diaphragm, the second diaphragm is arranged closer to the image element than the first diaphragm on the optical path, and the first diaphragm and the second diaphragm are diaphragms in different directions. Therefore, the light can be adjusted appropriately. This suppresses the occurrence of ghosts, for example, enables high-quality and wide-angle image display, provides high-quality images, and further downsizing the optical system, and thus downsizing the entire device. It becomes possible to plan.

In a specific aspect of the present invention, the projection optical system has at least one lens arranged between the diaphragm position of the first diaphragm and the diaphragm position of the second diaphragm.

According to another aspect of the present invention, in the two-stage structure diaphragm, one of the first diaphragm and the second diaphragm is integrally molded as a part of a lens barrel of the projection optical system, and the other is a lens barrel and a separate body. It is a mounting member. In this case, a two-stage structure diaphragm can be realized with a simple structure.

In yet another aspect of the present invention, the mounting member is a black sheet member. In this case, for example, a black sheet member made of black tape or the like can shield light.

In still another aspect of the present invention, the black sheet member is attached so as to wrap around at least a part of the lens forming the projection optical system. In this case, it is possible to improve the adhesion to the lens that constitutes the projection optical system, and to suppress the occurrence of light leakage and the like due to internal reflection near the lens and the influence thereof on the image light and the like.

In still another aspect of the present invention, the mounting member has a plurality of holes corresponding to a plurality of positioning bosses provided on the projection optical system or the lens barrel. In this case, at the time of assembling the mounting member, it is possible to suppress the occurrence of deflection and the deviation.

In still another aspect of the present invention, the positioning boss is arranged symmetrically in the projection optical system. In this case, the assembling accuracy can be improved.

In still another aspect of the present invention, the positioning boss contacts the projection optical system or the lens barrel to perform positioning in the optical axis direction. In this case, accurate positioning can be performed.

According to still another aspect of the present invention, the positioning boss and the plurality of holes corresponding to the boss have different shapes from the other bosses and holes. In this case, mistakes during assembly can be avoided.

10... Light guide member, 20... Light guide device, 30... Projection optical system, 50... Light transmission member, 80... Image display device, 100... Virtual image display device, 100A... First display device, 100B... Second display device, 102... Frame part, 102a... Central part, 102b... Support body, 104... Temple, 105d... Exterior member, 200... Virtual image display device, 230... Projection optical system, 280... Image display device, 300... Virtual image display device, 300A... 1st display device, AT... Attachment positioning part, AX... Optical axis, BR... Lens barrel, BS... Boss, CC... Center part, DS... Drawing stop, DT1-DT4... Positioning part, EB... Eye box, GL... Image Light, GLc... component light, GLp... component light, H1, H2... aperture, HL... hole, IP... image plane, LS... projection lens, LS1 to LS4... lens, MM... mounting member, OP1, OP2... aperture, PP... Peripheral part, PRc... Principal ray, PRp... Principal ray, ST1... First diaphragm, ST2... Second diaphragm, TP... Projection, .alpha.... Inclination angle, .beta.... Inclination angle

Claims (20)

A video element that displays an image,
A projection optical system for projecting an image from the video element,
A two-stage structure diaphragm having a first diaphragm that forms a first opening in the projection optical system and a second diaphragm that forms a second opening in the projection optical system;
The first diaphragm and the second diaphragm in the two-stage structure diaphragm are provided at different positions depending on the inclination of the principal ray of the image light emitted from the peripheral portion of the image plane of the image element. Display device. The virtual image display device according to claim 1, wherein an inclination of the chief ray with respect to the image plane is different between a first direction of in-plane directions of the image plane and a second direction perpendicular to the first direction. .. The surface of the eye box showing the range in which the virtual image can be visually recognized by the observer is larger than the vertical direction perpendicular to the horizontal direction in the horizontal direction along the line of the eyes at the time of observation,
The virtual image display device according to claim 2, wherein the first direction corresponds to the horizontal direction, and the second direction corresponds to the vertical direction. Regarding the inclination of the chief ray in the peripheral portion of the image element, the inclination in the second direction is larger than the inclination in the first direction,
In the two-stage structure diaphragm, the second diaphragm is arranged closer to the image element than the first diaphragm on the optical path, and the first diaphragm is a diaphragm in the first direction, and the second diaphragm The virtual image display device according to claim 2, wherein the diaphragm is a diaphragm in the second direction. The virtual image display device according to claim 4, wherein a second-direction opening width of the second opening is smaller than a first-direction opening width of the first opening. Regarding the inclination of the chief ray in the peripheral portion of the image element, the inclination in the second direction is smaller than the inclination in the first direction,
In the two-stage structure diaphragm, the second diaphragm is arranged closer to the image sensor than the first diaphragm on the optical path, and the first diaphragm is a diaphragm in the second direction, The virtual image display device according to claim 2, wherein the diaphragm is a diaphragm in the first direction. The virtual image display device according to claim 1, wherein the projection optical system forms an intermediate image to form an asymmetric optical system. The virtual image according to any one of claims 1 to 7, wherein the projection optical system has at least one lens arranged between the diaphragm position of the first diaphragm and the diaphragm position of the second diaphragm. Display device. In the two-stage structure diaphragm, one of the first diaphragm and the second diaphragm is integrally molded as a part of a lens barrel of the projection optical system, and the other is a mounting member which is separate from the lens barrel. The virtual image display device according to any one of claims 1 to 8. The virtual image display device according to claim 9, wherein the attachment member is a black sheet member. The virtual image display device according to any one of claims 1 to 10, further comprising a light guide member having a transmissive reflection surface that covers the front of the eyes when the observer is wearing the light guide member. A video element that displays an image,
A projection optical system for projecting an image from the video element,
A two-stage structure diaphragm having a first diaphragm that forms a first opening in the projection optical system and a second diaphragm that forms a second opening in the projection optical system;
In the two-stage structure diaphragm, the second diaphragm is arranged closer to the image element than the first diaphragm on the optical path, and the first diaphragm and the second diaphragm are diaphragms in different directions. Is a virtual image display device. The virtual image display device according to claim 12, wherein the projection optical system has at least one lens arranged between the diaphragm position of the first diaphragm and the diaphragm position of the second diaphragm. In the two-stage structure diaphragm, one of the first diaphragm and the second diaphragm is integrally molded as a part of a lens barrel of the projection optical system, and the other is a mounting member which is separate from the lens barrel. The virtual image display device according to claim 12, wherein the virtual image display device is provided. The virtual image display device according to claim 14, wherein the mounting member is a black sheet member. The virtual image display device according to claim 15, wherein the black sheet member is attached so as to wrap around at least a part of a lens forming the projection optical system. The virtual image display device according to claim 14, wherein the mounting member has a plurality of holes corresponding to a plurality of positioning bosses provided on the projection optical system or the lens barrel. The virtual image display device according to claim 17, wherein the positioning bosses are arranged symmetrically in the projection optical system. The virtual image display device according to any one of claims 17 and 18, wherein the positioning boss contacts the projection optical system or the lens barrel to perform positioning in the optical axis direction. The virtual image display device according to any one of claims 17 to 19, which includes, among the positioning boss and the plurality of holes corresponding to the boss, one having a different shape from the other bosses and holes.

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